The present invention relates to a technique for calculating exterior orientation parameters of a camera mounted on an aerial vehicle.
Technologies using an unmanned aerial vehicle (UAV) in aerial photogrammetry are publicly known. In these techniques, a three-dimensional model of an object to be surveyed is generated by using photographed images of the object, which are taken from a UAV. The object to be surveyed is, for example, a ground surface. According to this technique, orientation is first performed by using multiple photographed images containing the same object, to calculate exterior orientation parameters (location and attitude) of a camera mounted on the UAV, and a process relating to generation of a three-dimensional model is performed by using the exterior orientation parameters. The technique of calculating exterior orientation parameters of a camera in the field of aerial photogrammetry is, for example, disclosed in Japanese Unexamined Patent Application Laid-Open No. 2014-006148.
According to an existing technique, multiple orientation targets are installed on a ground surface, and the locations of the orientation targets are measured in advance. In this condition, exterior orientation parameters of a camera corresponding to each of aerial photographed images are calculated by a method of resection with use of the orientation targets contained in the aerial photographed images. This technique has a drawback in the costs relating to installation and positioning of the orientation targets. Moreover, installation of the orientation targets is difficult depending on geographic features.